Response Status Codes are not the Codes defined in spec

[ItsReddi]

According to the OAS 3 Spec, status codes that are available are defined in
https://tools.ietf.org/html/rfc7231#section-6

The generated code is returning 422 for example.
https://github.com/OAI/OpenAPI-Specification/blob/3.0.2/versions/3.0.2.md#httpCodes

These code is not defined in the RFC.
If i am correct it should return 400 instead.

Or for duplicate errors: 409

[cebe]

it should return the code you specify in your api description, but currently it simply uses Yii defaults.